The proposed clinical trial shall address a major question in the use of topical agents for breast cancer prevention ? drug distribution throughout the breast. The goal is to determine if there are similar breast tissue concentrations of telapristone throughout the breast with both oral and topical delivery. It is a phase IIb randomized double-blinded trial of oral vs. topical telapristone for 4 weeks prior to surgery in women undergoing mastectomy for stage 0-II breast cancer therapy or prophylaxis (for BRCA mutation, BRCA mutation carriers, women with strong family history or lobular carcinoma in situ or other conditions where prophylactic mastectomy has been elected) at Northwestern University, University of Chicago, and Memorial Sloan Kettering Cancer Center.